Deterministic stabilization of eight-way 2D diffractive beam combining using pattern recognition.

We demonstrate a new method for controlling diffractive, high-power beam combination, sensing phase errors by analyzing the intensity pattern of uncombined side beams at the output. A square array of eight beams is combined with <0.3% stability and 84.6% efficiency. As the channel count is increased, so does the usable information, enabling scaling to large channel counts without significant slowing of control loop response time, an advantage over single-input algorithms.

Ensuring Product Quality, Consistency and Patient Supply over Time for a Large-Volume Biologic: Experience with Remicade®.

Biologics are produced from living organisms in complex, multi-stage manufacturing processes and contain inherent variability, which must be understood and controlled during manufacturing to avoid unexpected changes in key quality attributes that may contribute to clinically meaningful differences. The process must also meet large commercial demand, while simultaneously being able to accommodate change without sacrificing product consistency. The four key components of successful biologics manufacturing are (1) a stable, well-defined proprietary cell line; (2) a good manufacturing practice (GMP)-compliant supply chain with a process control strategy defining acceptable levels of variability for target product/process attributes and capable of managing complex material flows; (3) a tightly controlled procedure for implementation of proposed process changes that ensures product consistency; and (4) built-in redundancy and flexibility providing the ability to adapt rapidly to unexpected developments. This report describes the requirements for the manufacturing and distribution of biologics, using Remicade® (infliximab, Janssen Biotech, Horsham, PA, USA) as an example of best practices. Since Remicade's first marketing approval in 1998, Janssen has manufactured > 150 million vials used to treat > 2.6 million patients around the world for a variety of inflammatory diseases. Remicade displays a highly consistent quality attribute profile and meets all product/process specifications across multiple manufacturing sites and process scales. Janssen's experience with Remicade demonstrates that deep product knowledge, extensive manufacturing experience, diligent product/process monitoring and a sustained commitment to compliance and research are required to ensure quality, consistency and uninterrupted patient supply for large-volume biologics over the long term.

Development of sub-100 femtosecond timing and synchronization system.

The precise timing and synchronization system is an essential part for the ultra-fast electron and X-ray sources based on the photocathode injector where strict synchronization among RF, laser, and beams are required. In this paper, we present an integrated sub-100 femtosecond timing and synchronization system developed and demonstrated recently in Tsinghua University based on the collaboration with Lawrence Berkeley National Lab. The timing and synchronization system includes the fiber-based CW carrier phase reference distribution system for delivering stabilized RF phase reference to multiple receiver clients, the Low Level RF (LLRF) control system to monitor and generate the phase and amplitude controllable pulse RF signal, and the laser-RF synchronization system for high precision synchronization between optical and RF signals. Each subsystem is characterized by its blocking structure and is also expansible. A novel asymmetric calibration sideband signal method was proposed for eliminating the non-linear distortion in the optical synchronization process. According to offline and online tests, the system can deliver a stable signal to each client and suppress the drift and jitter of the RF signal for the accelerator and the laser oscillator to less than 100 fs RMS (∼0.1° in 2856 MHz frequency). Moreover, a demo system with a LLRF client and a laser-RF synchronization client is deployed and operated successfully at the Tsinghua Thomson scattering X-ray source. The beam-based jitter measurement experiments have been conducted to evaluate the overall performance of the system, and the jitter sources are discussed.

Stable transmission of radio frequency signals on fiber links using interferometric delay sensing.

We demonstrate distribution of a 2850 MHz rf signal over stabilized optical fiber links. For a 2.2 km link we measure an rms drift of 19.4 fs over 60 h, and for a 200 m link an rms drift of 8.4 fs over 20 h. The rf signals are transmitted as amplitude modulation on a continuous optical carrier. Variations in the delay length are sensed using heterodyne interferometry and used to correct the rf phase. The system uses standard fiber telecommunications components.